Semiconductor device and manufacturing method of the same

ABSTRACT

The invention realizes excellent electrical and mechanical connection between electrodes in a packaging structure where a plurality of semiconductor chips having electrodes are connected with each other through the low-melting metallic members. Bump electrodes are formed on a front surface of a first semiconductor chip. Penetrating holes are formed in a second semiconductor chip, and a penetrating electrode having a gap in a center is formed in each of the penetrating holes. Low-melting metallic members are interposed between connecting surfaces of the bump electrodes and the penetrating electrodes, and a part of each of the low-melting metallic members flows in each of the gaps of the penetrating electrodes when dissolved. This prevents short-circuiting between the bump electrodes which is caused by oversupplying the low-melting metallic members between the adjacent bump electrodes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a semiconductor device manufacturing method,particularly to a packaging technology of a semiconductor device havingpenetrating electrodes.

2. Description of the Related Art

Conventionally, a packaging structure where a plurality of semiconductorchips having bump electrodes or penetrating electrodes are electricallyand mechanically connected with each other through members made oflow-melting metal such as solder is known.

FIGS. 8A and 8B are cross-sectional views for explaining a semiconductordevice manufacturing method of a conventional art. As shown in FIG. 8A,a passivation film 51 is formed on a front surface of a firstsemiconductor chip 50. A plurality of bump electrodes 52 is formed onthe front surface of the first semiconductor chip 50, and low-meltingmetallic members 53 are attached to tips of the bump electrodes 52.

On the other hand, a second semiconductor chip 60 is formed with aplurality of penetrating holes 61, and a penetrating electrode 62 madeof metal such as Cu (copper) is embedded in each of the penetratingholes 61. The penetrating electrodes 62 are formed protruding from aback surface (upper surface in FIG. 8A) of the second semiconductor chip60. The back surface of the second semiconductor chip 60 is covered witha passivation film 63 except a region formed with the penetratingelectrodes 62.

The first semiconductor chip 50 and the second semiconductor chip 60 aredisposed so that the bump electrodes 52 and the penetrating electrodes62 face each other with keeping a predetermined space therebetween. Theplurality of the bump electrodes 52 and the plurality of the penetratingelectrodes 62 are disposed on the first semiconductor chip 50 and thesecond semiconductor chip 60 respectively, at micro-pitches of about 20μm or less.

Next, as shown in FIG. 8B, the low-melting metallic members 53 aredissolved by heating, and the bump electrodes 52 and the penetratingelectrodes 62 are connected through the dissolved low-melting metallicmembers 53. The dissolved low-melting metallic members 53 are hardenedby cooling so that the bump electrodes 52 and the penetrating electrodes62 are electrically and mechanically connected with each other throughthe low-melting metallic members 53.

FIGS. 9A and 9B are cross-sectional views for explaining a semiconductordevice manufacturing method of other conventional art. In thisconventional art, a plurality of semiconductor chips having bumpelectrodes or penetrating electrodes are resin-sealed simultaneouslywith electrical and mechanical connection thereof through low-meltingmetallic members.

As shown in FIG. 9A, an optimal amount of metal-active thermosettingresin 64 is attached to the back surface (surface facing the firstsemiconductor chip 50) of the second semiconductor chip 60. Then, asshown in FIG. 9B, the low-melting metallic members 53 are dissolved byheating to connect the bump electrodes 52 and the penetrating electrodes62 through the dissolved low-melting metallic members 53, andsimultaneously with this connection the thermosetting resin 64 is filledin a space between the first semiconductor chip 50 and the back surfaceof the second semiconductor chip 60.

A heating temperature is chosen and materials of the low-meltingmetallic members 53 and the thermosetting resin 64 are selected so as toharden the thermosetting resin 64 by heating simultaneously withdissolution of the low-melting metallic members 53. Therefore, theelectrical and mechanical connection between the bump electrodes 52 andthe penetrating electrodes 62 and resin-sealing thereof can besimultaneously realized.

Such technologies are disclosed in the Japanese Patent ApplicationPublication No. Hei 10-12688.

In the conventional art shown in FIGS. 8A and 8B, however, if thelow-melting metallic members 53 are oversupplied, a short circuit canoccur between the adjacent electrodes as shown in FIG. 8B. The bumpelectrodes 52 and the penetrating electrodes 62 are disposed atmicro-pitches of about 20 μm or less, so that it has been difficult tocontrol a supply amount of the low-melting metallic members 53 properly.

Furthermore, in the other conventional art shown in FIGS. 9A and 9B,since the thermosetting resin 64 covers portions to be connected of thebump electrodes 52 and the penetrating electrodes 62 before connection,the thermosetting resin 64 can remain on the portions to be connected,i.e. surfaces to be connected of the bump electrodes 52 and thepenetrating electrodes 62. FIG. 9B shows thermosetting resin 64Aremaining on the portions to be connected. This reduces the electricalconnection area of the bump electrodes 52 and the penetrating electrodes62, so that resistance for connection increases or disconnection occursto degrade characteristics of electrical connection.

SUMMARY OF THE INVENTION

The invention provides a semiconductor device that includes a firstsemiconductor chip, a first electrode formed on a front surface of thefirst semiconductor chip, a second semiconductor chip facing the firstsemiconductor chip, a second electrode formed in a hole penetratingthrough the second semiconductor chip and having a hollow space along acenter of the penetrating hole, and an electrode connecting memberconnecting the first electrode and the second electrode. The electrodeconnecting member is interposed between connecting surfaces of the firstelectrode and the second electrode and penetrates into the hollow spaceof the second electrode.

The invention also provides a method of manufacturing a semiconductordevice. The method includes preparing a first semiconductor chip havinga first electrode and an electrode connecting member attached to a tipof the first electrode, preparing a second semiconductor chip having ahole penetrating through the second conductor chip and a secondelectrode formed in the hole so as to leave a hollow space along acenter of the hole, placing the first semiconductor chip and the secondsemiconductor chip so that the first electrode faces the secondelectrode, heating the electrode connecting member, and attaching thefirst electrode and the second electrode so that part of the heatedelectrode connecting member penetrates into the hollow space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional views for explaining a semiconductordevice and its manufacturing method of a first embodiment of theinvention.

FIG. 2 is a cross-sectional view for explaining a forming method of asemiconductor chip structure.

FIG. 3 is a cross-sectional view for explaining the forming method ofthe semiconductor chip structure.

FIG. 4 is a cross-sectional view for explaining the forming method ofthe semiconductor chip structure.

FIG. 5 is a cross-sectional view for explaining the forming method ofthe semiconductor chip structure.

FIG. 6 is a cross-sectional view for explaining the forming method ofthe semiconductor chip structure.

FIGS. 7A and 7B are cross-sectional views for explaining a semiconductordevice and its manufacturing method of a second embodiment of theinvention.

FIGS. 8A and 8B are cross-sectional views for explaining a semiconductordevice and its manufacturing method of a conventional art.

FIGS. 9A and 9B are cross-sectional views for explaining a semiconductordevice and its manufacturing method of other conventional art.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the invention will be described with reference toFIGS. 1A and 1B. As shown in FIG. 1A, a semiconductor integrated circuit(not shown) is formed on a front surface of a first semiconductor chip1. A passivation film 2 made of a silicon nitride film (SiN film) isformed to protect the semiconductor integrated circuit. A plurality ofbump electrodes 3 is formed on the front surface of the firstsemiconductor chip 1 as externally connecting terminals of thesemiconductor integrated circuit, and low-melting metallic members 4 aselectrode connecting members are attached to tips of the bump electrodes3.

The plurality of the bump electrodes 3 is made of a metal such as Cu,and can be formed by an electrolytic plating method. The bump electrodes3 are about 10 μm in thickness, and disposed at micro-pitches of about20 μm or less. The low-melting metallic members 4 are made of a metaldifferent from the metal forming the bump electrodes 3 or penetratingelectrodes 12, that is, metal having a lower melting point than themetal forming the bump electrodes 3 and the penetrating electrodes 12,such as solder and lead-free SnAg. The low-melting metallic members 4can be formed by the electrolytic plating method as well, and itsthickness is about 1.5 μm.

On the other hand, a plurality of penetrating holes 11 is formed in asecond semiconductor chip 10, and a penetrating electrode 12 made of ametal such as Cu is embedded in each of the penetrating holes 11. Thepenetrating electrodes 12 are hollow cylinders or hollow columns withpolygonal cross-section. That is, the penetrating electrode 12 has a gap13 in a center of the penetrating hole 11, and formed protruding from aback surface (upper surface in FIG. 1A) of the second semiconductor chip10 by some μm. If the second semiconductor chip 10 has a thickness of 50μm, the penetrating electrode 12 is longer than the thickness of thesecond semiconductor chip 10 by some μm. These penetrating electrodes 12are disposed at the same pitches as the bump electrodes 3 of the firstsemiconductor chip 1.

The back surface of the second semiconductor chip 10 is covered with apassivation film 14 made of a silicon nitride film (SiN film) except aregion formed with the penetrating electrodes 12. Furthermore, asemiconductor integrated circuit (not shown) is formed on a frontsurface (lower surface in FIG. 1A) of the second semiconductor chip 10.The penetrating electrodes 12 are used as externally connectingterminals of the semiconductor integrated circuit.

The first semiconductor chip 1 and the second semiconductor chip 10 aredisposed so that the bump electrodes 3 and the penetrating electrodes 12face each other keeping a predetermined space therebetween.

Next, as shown in FIG. 1B, the low-melting metallic members 4 aredissolved by heating, and the bump electrodes 3 and the penetratingelectrodes 12 are connected through the dissolved low-melting metallicmembers 4. This heating and connecting process can be performed by aflip chip bonder. At this time, part of each of the dissolvedlow-melting metallic members 4 flows in the gap 13 of the penetratingelectrode 12 pulled by capillarity pressure, so that short-circuiting isprevented between the adjacent bump electrodes 3.

Then, the dissolved low-melting metallic members 4 are hardened bycooling, and the bump electrodes 3 and the penetrating electrodes 12 areelectrically and mechanically connected through the low-melting metallicmembers 4. The connecting area of the penetrating electrode 12 with thelow-melting metallic member 4 increases as the low-melting metallicmember 4 is inserted in the gap 13 of the penetrating electrode 12 moredeep. This makes the electrical and mechanical connection between thepenetrating electrode 12 and the low-melting metal member 4 stable.After this, a resin is injected between the first semiconductor chip 1and the second semiconductor chip 10 for resin-sealing.

Next, an example of the forming method of the structure of the secondsemiconductor chip 10 will be described with reference to FIGS. 2 to 6.

As shown in FIG. 2, a grove 21 is formed in the front surface (surfaceformed with the semiconductor integrated circuit) of the secondsemiconductor chip 10 by a dry etching method. Then, a seed layer 22 forelectrolytic plating is formed on the whole front surface of the secondsemiconductor chip 10 including inside of the grove 21, and then Cuelectrolytic plating is performed to form a plating layer 23. Platingtime is controlled so as to stop plating before the plating layer 23completely fills the groove 21. A predetermined region of the seed layer22 is covered with a photoresist layer (not shown) so that the platinglayer 23 can be selectively formed to make necessary connection with thesemiconductor integrated circuit.

Next, as shown in FIG. 3, the back surface of the second semiconductorchip 10 is ground or etched to form the penetrating hole 11 and thepenetrating electrode 12 having the gap 13 in the center of thepenetrating hole 11.

Next, as shown in FIG. 4, the semiconductor on the back surface of thesecond semiconductor chip 10 is etched to protrude the penetratingelectrode 12.

Next, as shown in FIG. 5, the passivation film 14 made of a siliconnitride film (SiN film) is formed on the back surface of the secondsemiconductor chip 10 by a CVD (chemical vapor deposition) method. Inthis process, the protruding tip of the penetrating electrode 12 iscovered with the passivation film 14. As shown in FIG. 6, thepassivation film 14 covering the protruding tip of the penetratingelectrode 12 is ground by a CMP (chemical mechanical polishing) methodto expose the tip of the penetrating electrode 12. Thus, the structureof the penetrating electrode of the second semiconductor chip 10 isformed.

When a diameter of the penetrating hole 11 is 10 μm, it is preferable toset a thickness of the penetrating electrode 12 at about 1 μm and awidth of the gap 13 of the penetrating electrode 12 at about 8 μm.However, the invention is not limited to this number.

Next, a manufacturing method of a semiconductor device of a secondembodiment of the invention will be described with reference to FIGS. 7Aand 7B. Note that the same numerals are provided to the same portions asthose in FIGS. 1A and 1B, and description for the same portions will beomitted.

As shown in FIG. 7A, an optimal amount of the metal-active thermosettingresin 15 is attached to the back surface (surface facing the firstsemiconductor chip 1) of the second semiconductor chip 10 by adispenser. The thermosetting resin 15 can be attached to the frontsurface (surface facing the second semiconductor chip 10) of the firstsemiconductor chip 1 alternatively. A non-conductive paste can be usedas the thermosetting resin 15, for example.

As shown in FIG. 7B, the low-melting metallic members 4 are dissolved byheating. Then, the bump electrodes 3 and the penetrating electrodes 12are connected through the dissolved low-melting metallic members 4, andsimultaneously with this connection the thermosetting resin 15 is filledin the space between the first semiconductor chip 10 and the backsurface of the second semiconductor chip 10.

A heating temperature is chosen and materials of the low-meltingmetallic members 4 and the thermosetting resin 15 are selected, so as toharden the thermosetting resin 15 simultaneously with dissolution of thelow-melting metallic members 14. When the low-melting metallic members 4are made of SnAg, and the thermosetting resin 15 is made ofnon-conductive paste, the heating temperature is 240 to 300° C.

In this heating process, after the surfaces of the electrodes areactivated, part of the metal-active thermosetting resin 15 flows in eachof the gaps 13 of the penetrating electrodes 12 pulled by capillaritypressure before losing fluidity by thermosetting, and sequentially apart of each of the dissolved low-melting metallic members 4 flows ineach of the gaps 13 of the penetrating electrodes 12. Then, thethermosetting resin 15 is hardened by heating, and the dissolvedlow-melting metallic members 4 are hardened by cooling. Thethermosetting resin 15 keeps hardened even when cooled.

In this processing, only the low-melting metallic members 4 areinterposed between the connecting surfaces of the bump electrodes 3 andthe penetrating electrodes 12, and the thermosetting resin 15 isprevented from remaining therebetween, thereby providing excellentelectrical connection between the bump electrodes 3 and the penetratingelectrodes 12. Furthermore, insertion of part of the low-meltingmetallic member 4 in the gap 13 of the penetrating electrode 12 canincrease a connecting area of the low-melting metallic member 4 and thepenetrating electrode 12, thereby realizing an excellent packagingstructure where the thermosetting resin 15 contacts to the low-meltingmetallic member 4 and covers it in the gap 13.

Although the tip of the bump electrode 3 and the tip of the penetratingelectrode 4 having the gap are connected with each other in theconnecting structure of the first and second embodiments, the inventionis not limited to this but can be also applied to a structure where thetips of the penetrating electrodes 4 having the gaps are connected.

1. A semiconductor device comprising: a first semiconductor chip; afirst electrode formed on a front surface of the first semiconductorchip; a second semiconductor chip facing the first semiconductor chip; asecond electrode formed in a hole penetrating through the secondsemiconductor chip and having a hollow space along a center of thepenetrating hole; and an electrode connecting member connecting thefirst electrode and the second electrode, wherein the electrodeconnecting member is interposed between connecting surfaces of the firstelectrode and the second electrode and penetrates into the hollow spaceof the second electrode.
 2. The semiconductor device of claim 1, furthercomprising a sealing resin filling a space between the firstsemiconductor chip and the second semiconductor chip, wherein part ofthe sealing resin is located in the hollow space and in contact with theelectrode connecting member.
 3. The semiconductor device of claim 1,wherein a melting point of the electrode connecting member is lower thana melting point of the first electrode or a melting point of the secondelectrode.
 4. The semiconductor device of claim 2, wherein the sealingresin is a thermosetting resin.